1. Field of the Invention
The present invention relates to driving assistance devices and methods capable of detecting and assisting travel of a vehicle on a connection lane, i.e. a ramp lane connected to a driving lane on a highway, through which the vehicle leaves the highway.
2. Description of the Related Art
Recently, there have been proposed driving assistance devices capable of performing driving assistance for the driver of a vehicle. For example, a conventional driving assistance device detects a ramp lane as a connection lane connected to a driving lane on a highway (vehicle roadway), through which the vehicle leaves the highway.
A patent document, Japanese patent laid open publication No. JP 2008-189093 discloses a conventional vehicle driving control device capable of detecting the presence of a ramp lane, i.e. a connection lane connected to a driving lane on a highway, on the basis of navigation information transmitted from a vehicle navigation system mounted on the vehicle. The vehicle driving control device detects entry of the own vehicle into a ramp lane as a connection lane connected to a driving lane on a highway when:
(a) detecting the presence of a ramp lane;
(b) detecting or estimating occurrence of a driver's request to change a current driving lane on a highway; and
(c) detecting that the own vehicle crosses a dotted lane boundary line which divides the current driving lane from the ramp lane.
The conventional vehicle driving control device detects that the own vehicle has passed through a connection lane when detecting that the own vehicle has passed through a tollgate or is running on a general roadway or a parking space such as a highway rest stop on the basis of navigation information transmitted from the vehicle navigation system.
However, because the conventional vehicle driving control device disclosed in the patent document previously described detects a place of exit of the ramp lane as a connection lane on the basis of the navigation information transmitted from the vehicle navigation device, if no vehicle navigation system is mounted on a vehicle, it is impossible to apply the vehicle driving control device to the vehicle, and difficult for the driver of the vehicle to correctly detect a place of exit of the ramp lane, i.e. detect whether or not the own vehicle has passed the ramp lane, i.e. passed through the exit of the ramp lane.